As a method of casting anodes for electrolyzing copper, the Walker System, in which molten copper is poured into horizontally positioned molds M, as shown in FIG. 5, has been widely used.
That is, conventional molds M for anodes were made by pouring, as an example, refined blister copper with the copper grade of about 99.3% coming out of a refining furnace, which constitutes the last stage in a melt-refining process, into the molds formed in a prescribed shape with cast steel, etc. Such a shape contains, in general, a base 1 having the same shape as that of an anode and edges 2 which surround the outer circumference of the base 1 and at the same time protrude upwards from the upper plane 1a of the base 1 by a prescribed height. That is, the mold M for casting anode had a recess S which is defined by the upper plane 1a of the base 1 and inner circumferential planes 2a of the edges 2 which protrude upwards out of the upper plane 1a of the base, and molten copper consisting of refined blister copper was poured into this recess S for forming such anode A for electrolyzing copper as shown in FIG. 6.
However, when a horizontal casting was done using a mold M according to the Walker System as mentioned above, as molten copper was poured into the mold, fins were formed at the upper edges "e" of outer circumferences of the anode A, which correspond to interfaces between the mold M and the molten metal. It was very difficult to prevent the formation of such fins.
Also, such fins on an anode caused troubles in an anode aligning machine such as obstructing an insertion of starting sheets (cathodes) in a refining process of copper electrolysis, or caused an anode to come in contact with other anodes, causing a short-circuiting at the time of the electrolysis, thus lowering the current efficiency.
In an effort to overcome such troubles, adjustments were made in a molten metal temperature, a speed of pouring molten metal and a height of cast metal, etc, but none of such adjustment trials provided truly effective finning preventive method. Also it was difficult to control the conditions in such adjustment methods to a uniform level. Thus, such approaches could not secure a satisfactory finning preventive technology.
Therefore, the present inventors provided, for a purpose of solving such problems as mentioned above, a casting method of anodes for electrolyzing copper as disclosed by the publication of the Patent Laid Open No.5(1993)-309471. In this casting method for anodes for electrolyzing copper, the generation of fins could be effectively prevented by coating inner circumferential planes of a mold with finning preventive agent, which had a flash point of 190.degree. C..about.230.degree. and a kinematic viscosity of more than 50 cSt, by a ratio of 50 ml/m.sup.2 150 ml/m.sup.2, before pouring the molten copper into the mold.
Also this casting method could be satisfactorily carried out with a casting apparatus for anodes for electrolyzing copper, which comprised, as shown in FIG. 7, a mold transfer means 60 for retaining a mold M in a horizontal posture and transferring it along a predetermined transfer path; and an application apparatus 50 for finning preventive agent being provided above the mold transfer means 60 across the transfer path of the mold, and in which the application apparatus 50 for finning preventive agent had a plurality of spray nozzles 51, finning preventive agent supply pipes 52 which supplied the finning preventive agent from a finning preventive agent supply source to each one of the spray nozzles 51; and control devices 53 which controlled the feeding and no-feeding of the finning preventive agent to each spray nozzle 51 were provided.
In this casting apparatus, the finning preventive agent from the spray nozzles 51 could be sprayed over inner circumferential planes 2a.sub.1 .about.2a.sub.10 of the mold, while the feeding and no-feeding of the agent were controlled by the control devices 53.
However, when the inner circumferential planes 2a.sub.1 .about.2a.sub.10 of the mold M were coated with finning preventive agent by such casting method for anode for electrolysis of copper as mentioned above, it was difficult to completely prevent the generation of fins due to a clogging of the spray nozzles and uneven coating with sprays. Also, as a great amount of the finning preventive agent had to be sprayed for completely coating the inner circumferential planes of the mold with the finning preventive agent, the method was not economical.